Havana: Secretary of State John Kerry called Friday for "genuine democracy" in Cuba as the American flag was raised over a US embassy in Havana for the first time in 54 years.

Putting a symbolic capstone on the United States` historic rapprochement with Cuba, Kerry gave the cue to hoist the Stars and Stripes over the glass-and-concrete building on the Havana waterfront.

Three retired Marines who lowered the flag that day, as Washington severed ties with Havana at the height of the Cold War, were on hand to give the new flag to the Marine guard now charged with security at the embassy.

The historically charged photo-op put a coda on the historic rapprochement announced on December 17 by US President Barack Obama and Cuban counterpart Raul Castro, which paved the way for the two countries to reopen their embassies on July 20.

Kerry, the first secretary of state to visit Cuba since 1945, said the shift in US policy did not mean Washington would stop pressing for change on the communist island.

"The leaders in Havana and the Cuban people should also know that the United States will always remain a champion of democratic principles and reforms," he said.

"We remain convinced the people of Cuba would be best served by a genuine democracy where people are free to choose their leaders with commitment, economic and social justice."

The thawing in the Cold War conflict has been criticized by Obama`s conservative opponents.

Rubio, a Cuban-American senator from Florida, slammed the Obama administration for the absence of Cuban dissidents from the flag-raising ceremony.

"All the people in Cuba fighting for democracy, when they protest, they are rounded up, arrested and beaten. None of them were invited to this event," he told Fox News.

Cuban dissidents have expressed concern that the thaw between the two governments will leave them out in the cold.

But Kerry insisted the breakdown in ties and the US trade embargo on the island had failed to force Cuba to reform -- and that a new path must be sought.

"There will be hiccups along the way but it`s a start," he told reporters travelling with him on the whirlwind one-day trip.

He planned to meet with dissidents at a private reception later in the day.

Kerry was also due to take a stroll through Old Havana and meet ordinary Cubans in the historic colonial district.

He will not, however, meet with either Castro or his elder brother Fidel, the icon who led Cuba from its 1959 revolution until his retirement in 2006.Underlining the sticking points still complicating relations between the two countries, Fidel Castro said in an essay published in Cuban state media Thursday -- his 89th birthday -- that the United States owes Cuba "many millions of dollars" because of the US trade embargo on the island.

He did not detail exactly how much money he believed was due, but Cuba said in September the half-century-old embargo had cost it $116 billion.

The United States for its part says Cuba owes $7 billion to American citizens and companies whose property was seized after Castro came to power.

The Castro government will use Kerry`s visit to push for the lifting of the full embargo, in place since 1962.

Obama has called for an end to the embargo, but faces an uphill battle as he needs approval from Congress, where both houses are currently controlled by his Republican opponents -- many of them deeply hostile to communist Cuba.

Traveling with Kerry, Democratic Senator Patrick Leahy of Vermont said lifting the embargo was the fastest way to bring to change to Cuba.

"If we lift the embargo they won`t be able to blame everything on us and I think change will come far more rapidly," he said.

In eight months of negotiations since the rapprochement was announced, the two sides have made progress on a number of other divisive issues, most notably the removal of Cuba from the United States` list of "state sponsors of terrorism."

But unresolved sources of tension include the US naval base in Guantanamo Bay and Cuba`s treatment of the media, activists and dissidents.